Adaptive decision-making requires both attention to relevant environmental stimuli and accurate estimation of the consequences of possible actions. Disruption of these processes is devastating to mental health, and is common to numerous mental disorders including schizophrenia, addiction, obsessive-compulsive disorders, and attention-deficit disorders. Despite the importance of attention and choice option valuation, little is known about the neural mechanisms that underlie these processes, and ultimately drive decisions. The proposed research will describe the attentional dynamics that underlie and influence choice valuation, and will thus provide a better understanding of the human decision-making process. First, through electrophysiological recording of attention-related signals in monkey prefrontal cortex, we will examine how attentional resources are divided and dynamically allocated between two visual targets. While current models of human divided attention address the ability to attend to two spatially distinct stimuli, the underlying mechanisms and temporal dynamics behind divided attention are still a mystery. By understanding precisely how information is continuously gathered from two visual targets, we will begin to understand how two or more choice options can be valuated and compared during a value-based choice. Next, by examining these attentional dynamics during a choice itself and modulating spatial attention with electrical microstimulation of prefrontal cortex, we will determine how attention interacts with option valuation during a value-based choice. Recent research and numerous choice models suggest that an object's valuation depends greatly on the attentional resources allocated to it. By monitoring attention signals during a choice we can address this hypothesis, and by experimentally modulating attention with microstimulation we will attempt to directly affect the valuation process. The grand product of this work will be a mechanistic model of the role of attention in a value-based decision. The results will impact our knowledge of healthy, adaptive decision-making as well as the disorders that can devastate this complex behavior. Schizophrenia, addiction, and attention-deficit disorders affect millions of Americans, and share a common trait: the disruption of the pathway required to attend to, valuate, and make the best choice out of many options. This research will investigate how the attention and valuation processes occur and interact in the brain, providing a strong foundation from which to study these mental disorders.